Document Type : Original Article

Authors

1 World Health Organization, Benin City, Nigeria

2 Cedar Centre for Health and Development, Ekpoma, Nigeria

3 World Health Organization, Port Harcourt, Nigeria

4 nstitute of Lassa Fever Research and Control, ISTH, Irrua, Nigeria

5 Edo State Ministry of Health, Benin City, Nigeria

6 Nigeria Centre for Disease Control (NCDC) Surveillance Desk, ISTH, Irrua, Nigeria

Abstract

Background
Edo State has recorded recurrent Lassa fever (LF) outbreaks in the past and had the highest proportion of confirmed cases in Nigeria in 2018. The aim of this study was to profile Lassa fever contacts and demonstrate the implications of contact tracing in the control of the disease.
Methods
This is a cross-sectional study which was based on secondary analysis of information derived from Lassa fever contact tracing forms used during the response to the LF outbreak of 2018 in Edo State. Contact tracing and data management were part of WHO’s support to the State. Using SPSS, associations and other relationships between selected variables were tested. The significance level was set at p< 0.05.
Results
Total contacts followed up were 2527 during the period under consideration. Higher mean contacts per case (CPC) was significantly associated with contacts in Edo South, with contacts of cases that died and with cases with symptomatic contacts (F= 8.307, p<0.001; t= 14.995, p<0.001; t= 6.161, p= 0.014 respectively). Following the integration of contact tracing with awareness campaigns, the number of newly diagnosed cases per week dropped from over 30 in the 7th week to 2 in the 13th week (42 days or 2 incubation periods).
Conclusion
Effective contact tracing contributed significantly to the identification of symptomatic contacts and to rapid control of the 2018 Lassa fever outbreak in Edo State. We recommend the deployment of effective contact tracing in the control of outbreaks of viral haemorrhagic fevers especially Lassa fever.

Keywords

1.        Yun NE, Walker DH. Pathogenesis of lassa fever. Viruses. 2012;4(1):2031–48.
2.        Ogbu O, Ajuluchukwu E, Uneke CJ. Lassa fever in West African sub-region: An overview. J Vector Borne Dis. 2007;44(1):1–11.
3.        Fichet-Calvet E, Rogers DJ. Risk maps of lassa fever in West Africa. PLoS Negl Trop Dis. 2009;3(3).
4.        NCDC. An update of Lassa fever outbreak in Nigeria [Internet]. Disease Situation Reports. 2018 [cited 2018 Dec 5]. Available from: https://ncdc.gov.ng/diseases/sitreps
5.        Bremer V. Contact tracing [Internet]. Field Epidemiology Manual. 2019 [cited 2019 Mar 25]. Available from: https://wiki.ecdc.europa.eu/fem/w/wiki/1245.contact-tracing
6.        Gilsdorf A, Morgan D, Leitmeyer K. Guidance for contact tracing of cases of Lassa fever, Ebola or Marburg haemorrhagic fever on an airplane: Results of a European expert consultation. BMC Public Health [Internet]. 2012;12(1):1014–22. Available from: BMC Public Health
7.        WHO, CDC. Implementation and management of contact tracing for Ebola virus disease. 2015;(September):1–36.
8.        Armbruster B, Brandeau ML. Contact tracing to control infectious disease: when enough is enough. Heal Care Manag Sci. 2007;10(4):341–55.
9.        Centers for Disease Control and Prevention. What is contact tracing? [Internet]. 2016 [cited 2019 Feb 25]. Available from: https://www.cdc.gov/vhf/ebola/pdf/contact-tracing.pdf
10.      Ohuabunwo C, Ameh C, Oduyebo O, Ahumibe A, Mutiu B, Olayinka A, et al. Clinical profile and containment of the Ebola virus disease outbreak in two large West African cities, Nigeria, July–September 2014. Int J Infect Dis [Internet]. 2016;53:23–9. Available from: http://dx.doi.org/10.1016/j.ijid.2016.08.011
11.      Adi V. Gundlapalli, Cheryl S. Leung, Stephen W. Hwang, Minnie M. Ho, Alex Kiss. Infectious Disease Exposures and Contact Tracing in Homeless Shelters. J Health Care Poor Underserved. 2008;19(4):1163–7.
12.      Mohr O, Hermes J, Schink SB, Askar M, Menucci D, Swaan C, et al. Development of a risk assessment tool for contact tracing people after contact with infectious patients while travelling by bus or other public ground transport: A Delphi consensus approach. BMJ Open. 2013;3(10):1–10.
13.      Segynola AA. Geographical regions of Edo State. Ekpoma: Ambrose Alli University Press; 2011. 1–62 p.
14.      Edo State Government of Nigeria. Edo people [Internet]. 2017 [cited 2017 Jan 1]. Available from: http://www.edostate.gov.ng/edo-people/
15.      Danon L, Ford AP, House T, Jewell CP, Keeling MJ, Roberts GO, et al. Networks and the Epidemiology of Infectious Disease. Interdiscip Perspect Infect Dis [Internet]. 2011;2011:1–28. Available from: http://www.hindawi.com/journals/ipid/2011/284909/
16.      Fauci AS, Morens DM. The Perpetual Challenge of Infectious Diseases. N Engl J Med [Internet]. 2012;366(5):454–61. Available from: http://www.nejm.org/doi/abs/10.1056/NEJMra1108296
17.      Edmunds WJ, Hens N, Mikolajczyk R, Massari M, Heijne J, Auranen K, et al. Social Contacts and Mixing Patterns Relevant to the Spread of Infectious Diseases. PLoS Med. 2008;5(3):e74.
18.      Volz EM, Miller JC, Galvani A, Meyers L. Effects of heterogeneous and clustered contact patterns on infectious disease dynamics. PLoS Comput Biol. 2011;7(6).
19.      WHO Edo State Office. Contact tracing data base. Benin City: WHO Data Office; 2018.
20.      Ireye F, Aigbiremolen AO, Mutbam KS, Okudo I, Famiyesin EO, Asogun D, et al. An Assessment of Onset-to-Intervention Time and Outcome of Lassa Fever during an Outbreak in Edo State , Nigeria. Int J Prev Treat. 2018;7(1):1–5.
21.      Tambo E, Adetunde OT, Olalubi OA. Re-emerging Lassa fever outbreaks in Nigeria: Re-enforcing “One Health” community surveillance and emergency response practice. Infect Dis Poverty. 2018;7(1):1–7.
22.      Saka JM, Bintu Gubio A, Kerecvel YS, Saka AO, Oyemakinde A. Lassa fever epidemic in Nigeria- Outbreak investigation, risk factors and empirical analysis from 2012 To 2016. J Community Public Heal Nurs [Internet]. 2017;03(02). Available from: https://www.omicsonline.org/open-access/lassa-fever-epidemic-in-nigeria--outbreak-investigation-risk-factors-andempirical-analysis-from-2012-to-2016-2471-9846-1000170.php?aid=89379
23.      House T, Keeling MJ. The impact of contact tracing in clustered populations. PLoS Comput Biol. 2010;6(3):e1000721.
24.      Colman E, Spies K, Bansal S. The reachability of contagion in temporal contact networks: How disease latency can exploit the rhythm of human behavior. BMC Infect Dis. 2018;18(1):1–10.
25.      Oloniniyi OK, Unigwe US, Okada S, Kimura M, Koyano S, Miyazaki Y, et al. Genetic characterization of Lassa virus strains isolated from 2012 to 2016 in southeastern Nigeria. PLoS Negl Trop Dis. 2018;12(11):1–13.
26.      Nigeria Centre for Disease Control. Early results of Lassa virus sequencing and implications for current outbreak response in Nigeria [Internet]. 2018. Available from: https://reliefweb.int/report/nigeria/early-results-lassa-virus-sequencing-implications-current-outbreak-response-nigeria